Using the facultative anaerobic bacterium Rhodopseudomonas spheroides we are studying induced membrane development and its relationship to the plasma membrane. Experiments, employing one or more of the following: protein chemistry, immunochemistry, membrane mutants, physiochemical studies and and in vivo analyses of membrane growth enable us to establish the following: 1. Relationship(s) of plasma membrane protein to intracytoplasmic membrane protein. 2. Role of plasma membrane protein(s) in intracytoplasmic membrane induction. 3. Effects of light and oxygen on the induction and repression- depression of intracytoplasmic membrane biogenesis. 4. Biologic stability and replication of intracytoplasmic membranes. 5. Topological and temporal sequences of membrane development. 6. Structural interrelationships of intracytoplasmic membrane proteins and lipids.